Questions & Answers about La clessidra è già vuota.
In Italian, the definite article is used more often than in English. La clessidra means the hourglass.
Here, la is the feminine singular definite article, used because clessidra is a feminine singular noun.
So:
- la clessidra = the hourglass
- una clessidra = an hourglass / an hourglass
Italian usually does not drop the article in a sentence like this.